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Math Help - simple trig

  1. #1
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    simple trig

    find all the values of a in the range 0 deg to 360 deg satisfying 2sina = 3cosa

    i know its simple but just cant remember how to do it
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  2. #2
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    do i just divide sin and cos for tan?
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  3. #3
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    Hello djmccabie
    Quote Originally Posted by djmccabie View Post
    find all the values of a in the range 0 deg to 360 deg satisfying 2sina = 3cosa

    i know its simple but just cant remember how to do it
    Quote Originally Posted by djmccabie View Post
    do i just divide sin and cos for tan?
    Yes, you do, but remember that you must make sure that what you're dividing by is not zero. So you need to say:

    2\sin a = 3\cos a

    \Rightarrow 2\tan a = 3, provided \cos a \ne 0

    Then check that \cos a = 0 does not give any valid solutions and proceed with

    \Rightarrow \tan a = 1.5

    Grandad
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  4. #4
    A riddle wrapped in an enigma
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    Quote Originally Posted by djmccabie View Post
    do i just divide sin and cos for tan?
    Hi dj,

    Yep, pretty much.

    2 \sin a = 3 \cos a

    \frac{\sin a}{\cos a}=\frac{3}{2}

    \tan a = \frac{3}{2}

    Now, can you find the two angles that satisfy the original equation?
    Last edited by masters; April 13th 2009 at 08:31 AM.
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